public class Completion090PostingsFormat
This PostingsFormat is basically a T-Sink for a default postings
format that is used to store postings on disk fitting the lucene APIs and
builds a suggest FST as an auxiliary data structure next to the actual
postings format. It uses the delegate postings format for simplicity to
handle all the merge operations. The auxiliary suggest FST data structure is
only loaded if a FieldsProducer is requested for reading, for merging it uses
the low memory delegate postings format.